Engine out cold-start emissions generated before light-off of an exhaust system catalytic converter may contribute a large percentage of the total exhaust emissions. To expedite the attainment of the catalyst light-off temperature, engine systems have been developed that may increase an amount of fuel injected during startup to substantially increase the exhaust temperature to thereby decrease the light-off time of the catalytic converter.
However, the inventors herein have recognized issues with such an approach. As one example, the increase in the amount of fuel injected during startup may lower the engine operating efficiency and reduce fuel economy performance of the vehicle.
Thus, in one example, the above issue may be addressed by a system or a method of operating a vehicle including an engine. The engine may include at least one cylinder, a boosting device to boost intake air to the at least one cylinder, a fuel tank, a fuel vapor canister to store fuel vapors vented from the fuel tank, and an emission control device to treat exhaust gas from the engine. The boosting device includes a compressor at least partially driven by an electric motor. The method includes during an engine cold start condition, operating the electric motor of the boost device to boost intake air, directing the boosted intake air through the fuel vapor canister to release a fuel vapor stored in the fuel vapor canister, directing the fuel vapor from the fuel vapor canister to the engine, and performing combustion in the at least one cylinder using the fuel vapor during the engine starting.
By providing fuel vapor for combustion, cylinder wall wetting as a result of liquid fueling that would inhibit cylinder wall heating may be reduced. In this way, during a cold start condition, cylinder heating and correspondingly emission control device heating may be improved. Moreover, by using a boosting device to provide fuel vapor from the fuel vapor canister, fuel vapor may be used for combustion during combustion to improve air-fuel mixing and thus reduce starting emissions before a catalyst has reached its light-off temperature. In this way, fuel efficiency may be improved and vehicle emissions may be reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.